A Dictionary of Modern English Usage by H. W. Fowler
Oxford at the Clarendon Press, London, 1926
Split Infinitives. The English-speaking world may be divided into (1) those who neither know nor care what a split infinitive is; (2) those who do not know, but care very much; (3) those who know and condemn; (4) those who know and approve; and (5) those who know and distinguish.
1. Those who neither know nor care are the vast majority, and are a happy folk, to be envied by most of the minority classes; “to really understand” comes readier to their lips and pens than “really to understand,” they see no reason why they should not say it (small blame to them, seeing that reasons are not their critics’ strong point) and they do say it, to the discomfort of some among us, but not to their own.
2. To the second class, those who do not know but do care, who would as soon be caught putting their knives in their mouths as splitting an infinitive but have hazy notions of what constitutes that deplorable breach of etiquette, this article is chiefly addressed. These people betray by their practice that their aversion to the split infinitive springs not from instinctive good taste, but from tame acceptance of the misinterpreted opinion of others; for they will subject their sentences to the queerest distortions, all to escape imaginary split infinitives. “To really understand” is a split infinitive; “to really be understood” is a split infinitive; “to be really understood” is not one; the havoc that is played with much well-intentioned writing by failure to grasp that distinction is incredible. Those upon whom the fear of infinitive splitting sits heavy should remember that to give conclusive evidence, by distortions, of misconceiving the nature of the split infinitives is far more damaging to their literary pretensions than an actual lapse could be; for it exhibits them as deaf to the normal rhythm of English sentences.
No sensitive ear can fail to be shocked, if the following examples are read aloud, by the strangeness of the indicated adverbs. Why on earth, the reader wonders, is that word out of its place? He will find, on looking through again, that each has been turned out of a similar position, viz between the word “be” and a passive participle. Reflection will assure him that the cause of dislocation is always the same—all these writers have sacrificed the run of their sentences to the delusion that “to be really understood” is a split infinitive.
It is not; and the straitest non-splitter of us all can with a clear conscience restore each of the adverbs to its rightful place [for example, from a variety of newspaper articles]:
He was proposed at the last moment as a candidate likely generally to be accepted.
When the record of this campaign comes dispassionately to be written, and in just perspective, it will be found that
The leaders have given instructions that the lives and property of foreigners shall scrupulously be respected.
New principles will have boldly to be adopted if the Scottish case is to be met.
This is a very serious matter, which clearly ought to be further to be inquired into.
There are many points raised in the report which need carefully to be explored.
Only two ways of escaping from the conflict without loss, by this time become too serious squarely to be faced, have ever offered themselves.
The Headmaster of a public school possesses very great powers, which ought most carefully and considerately to be exercised.
The time to get this revaluation put through is when the amount paid by the State to the localities is very largely to be increased.
But the party whose Leader in the House of Commons acts in this way cannot fail deeply to be discredited by the way in which he flings out and about these false charges.
3. The above writers are bogyhaunted creatures who for fear of splitting an infinitive abstain from doing something quite different, i.e. dividing be from its complement by an adverb.
Those who presumably do know what split infinitives are, and condemn them, are not so easily identified, since they include all who neither commit the sin nor flounder about in saving themselves from it, all who combine with acceptance of conventional rules a reasonable dexterity. But when the dexterity is lacking, disaster follows. It does not add to a writer’s readableness if readers are pulled up now and again to wonder—why this distortion? Ah, to be sure, a non-split die-hard!
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